Fluid delivery devices, such as ambulatory infusion pumps, for example, have been developed for delivering liquid medicaments to a patient. Many such pumps or drug delivery devices are able to provide both steady state delivery (“basal delivery”) and instantaneous bursts of a predetermined amount of drug (“bolus delivery”) as required. In many instances, it is beneficial to provide a basal delivery of a drug which may be supplemented by a bolus delivery as well. For example, insulin for diabetes treatment as well as patient controlled analgesia for chronic pain treatment may be administered both at a continuous basal rate of delivery as well as via bolus amounts of delivery. Many such drug delivery devices are compact and able to be fixed to the user or patient during use and subsequently disposed of when the treatment is finished.
Many attempts have been made to provide continuous or near continuous basal delivery of such medicaments using various pump systems. The accuracy of the basal delivery rate often varies when the volume of the drug being delivered is small. Many fluid delivery devices include a reservoir to contain the liquid medicament and use various mechanical, gas, or electromechanical pumping or metering technologies to deliver the medicament to the patient via a needle or other catheter inserted transcutaneously, or through the skin of the patient.